Featured Research

from universities, journals, and other organizations

Structure discovered for promising tuberculosis drug target

Date:
October 25, 2012
Source:
Johns Hopkins Medicine
Summary:
Researchers have figured out the three-dimensional shape of the protein responsible for creating unique bonds within the cell wall of the bacteria that cause tuberculosis. The bonds make the bacteria resistant to currently available drug therapies, contributing to the alarming rise of these super-bacteria throughout the world.

A 3-D model of the outside surface of the enzyme that helps M. tuberculosis bacteria resist common antibiotics. Blue indicates positively charged atoms; red indicates negatively charged atoms. A peptidoglycan (green) is bound inside the enzyme’s active site.
Credit: Mario A. Bianchet

Researchers at Johns Hopkins have figured out the three-dimensional shape of the protein responsible for creating unique bonds within the cell wall of the bacteria that cause tuberculosis. The bonds make the bacteria resistant to currently available drug therapies, contributing to the alarming rise of these super-bacteria throughout the world.

With the protein structure in hand, the scientists say, drug designers have a clear way forward for weakening the cell wall and killing these deadly bacteria. Their results are reported in a paper published online Oct. 25 in Structure.

“We’ve known for a while that this protein would make a good drug target, but without a structural model, drug discovery is like blindly choosing random objects to fit into a small hole of unknown shape and size. The results of our study have removed the blindfold,” says L. Mario Amzel, Ph.D., professor and director of the Department of Biophysics and Biophysical Chemistry at The Johns Hopkins University School of Medicine.

The Johns Hopkins team used a technique called X-ray crystallography to scatter radiation off a specially prepared portion of the enzyme that forms the unique molecular bonds within the cell wall of Mycobacterium tuberculosis. They then used information about the direction and intensity of the radiation scattered to build a 3-D model of the arrangement of atoms in the enzyme.

Mario A. Bianchet, Ph.D., assistant professor of neurology at Johns Hopkins and a member of the research team, says the challenge of TB infection is that most of the long and costly standard drug treatment is just to get rid of the roughly 1 percent of bacteria that persist after the first week of a patient’s treatment. “The ‘persisters’ resist in part because of unique bonds within their cell walls. Their cell walls form a thick, three-layered boundary between the bacteria and the outside world, including a middle layer of interlocking molecules, called peptidoglycans, that form a network resembling a chain-link fence,” says Bianchet.

Peptidoglycans are long chains of individual sugar molecules with short protein branches extending from every other sugar on alternating sides of the chain. Specific enzymes bond the protein branches to each other to create a meshwork. In most species of bacteria, Amzel says, the majority of the bonds between these branches are created between position 4 on one branch and position 3 on an opposing branch. In M. tuberculosis, however, the majority of the bonds are created between positions 3 on both branches. The most common antibiotics interfere with the enzyme that creates the 4-3 bonds, which is enough to destabilize the cell wall and kill most of the TB bacteria.

The bacteria that persist have a particularly high level of 3-3 bonds between the peptidoglycan chains in their cell walls. These 3-3 bonds are created by a different enzyme, the one that Amzel and Bianchet studied, which is not specifically targeted by any current drugs. In addition to showing the structure of the enzyme, the team also showed a peptidoglycan molecule inside the action site where the 3-3 bonds are made, giving drug designers even more details about the way the protein works.

Amzel adds that “beyond fighting TB, the structure of this enzyme may help us fight other disease-causing bacteria that have similar enzymes, such as Enterococcus faecium and the spore-forming, drug-resistant Clostridium difficile.”

Other authors on the paper include Sabri Erdemli, Radhika Gupta, William Bishai and Gyanu Lamichhane from The Johns Hopkins University.

This work was supported by grants from the National Institutes of Health Office of the Director (DP2OD008459) and the National Institute of Allergy and Infectious Diseases (1R56AI087749).

On the Web:
Link to article

Amzel Lab


Story Source:

The above story is based on materials provided by Johns Hopkins Medicine. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins Medicine. "Structure discovered for promising tuberculosis drug target." ScienceDaily. ScienceDaily, 25 October 2012. <www.sciencedaily.com/releases/2012/10/121025121833.htm>.
Johns Hopkins Medicine. (2012, October 25). Structure discovered for promising tuberculosis drug target. ScienceDaily. Retrieved September 3, 2014 from www.sciencedaily.com/releases/2012/10/121025121833.htm
Johns Hopkins Medicine. "Structure discovered for promising tuberculosis drug target." ScienceDaily. www.sciencedaily.com/releases/2012/10/121025121833.htm (accessed September 3, 2014).

Share This



More Health & Medicine News

Wednesday, September 3, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Snack Attack: Study Says Action Movies Make You Snack More

Snack Attack: Study Says Action Movies Make You Snack More

Newsy (Sep. 2, 2014) You're more likely to gain weight while watching action flicks than you are watching other types of programming, says a new study published in JAMA. Video provided by Newsy
Powered by NewsLook.com
U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Doctors Fear They're Losing Battle Against Ebola

Doctors Fear They're Losing Battle Against Ebola

AP (Sep. 2, 2014) As a third American missionary is confirmed to have contracted Ebola in Liberia, doctors on the ground in West Africa fear they're losing the battle against the outbreak. (Sept. 2) Video provided by AP
Powered by NewsLook.com
Tech Giants Bet on 3D Headsets for Gaming, Healthcare

Tech Giants Bet on 3D Headsets for Gaming, Healthcare

AFP (Sep. 2, 2014) When Facebook acquired the virtual reality hardware developer Oculus VR in March for $2 billion, CEO Mark Zuckerberg hailed the firm's technology as "a new communication platform." Duration: 02:24 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins